Chlorophyll fluorescence
How do you measure plant fluorescence?
What is chlorophyll fluorescence analysis?
Chlorophyll fluorescence is a non-invasive measurement of photosystem II (PSII) activity and is a commonly used technique in plant physiology.
Chlorophyll fluorescence
Chlorophyll fluorescence is a non-invasive measurement of photosystem II (PSII) activity and is a commonly used technique in plant physiology.
To measure chlorophyll fluorescence choose the <Fluo> and <SP-analysis> mode . A typical set up includes measuring light at 12 μmol/m 2 /s, the saturated pulse (SP) at 10,000 μmol/m 2 /s for 800 ms and the actinic light at 70 μmol/m 2 /s.
Chlorophyll fluorescence (CF) is now adopted by the seed industry as a new technology that is applicable for effective characterisation of seed quality . Chlorophyll a in the seed coat was excited by laser radiation (670 nm) and the resulting fluorescence was measured instantaneously and non-destructively.
Measurements of plant water potential are primarily by means of either psychrometric methods (involving tissue equilibration with air in an enclosed chamber and the estimation of the vapour pressure using wet and dry thermocouples) or by means of the pressure chamber .
Commercial Instruments. Gas exchange is used most often as the way to measure photosynthesis , and there are a few different techniques. CO2 measurement uses infrared light, while O2 measurement requires electrochemical sensors. Infrared Gas Analyzer: CO2 absorbs infrared light.
Photorespiration (also known as the oxidative photosynthetic carbon cycle or C 2 cycle) refers to a process in plant metabolism where the enzyme RuBisCO oxygenates RuBP, wasting some of the energy produced by photosynthesis .
When light sufficient to drive photosynthesis is applied to a leaf after a period of darkness, there is a transient rise (usually for a few seconds) in the level of chlorophyll fluorescence that is usually the result of the reduction of electron carriers in the thylakoid membrane .
Chlorophyll is the substance that gives plants their green color. It helps plants absorb energy and get their nutrients from sunlight during a biological process known as photosynthesis .
Anthocyanins protect leaves from the stress of photoinhibitory light fluxes by absorbing the excess photons that would otherwise be intercepted by chlorophyll b .
To measure a plant’s growth rate, use a ruler or measuring tape to measure from the base of the plant to its highest point . If your plant is in a pot, start your measurement at the base of the pot. Write the measurement down, then repeat 2-3 days later.
An auxanometer (Gr. auxain= “to grow” + metron= “measure”) is an apparatus for measuring increase of growth in plants.
The equation for the growth rate formula is {frac {(S2-S1)}{T}}where S1=first measurement, S2=second measurement, and T equals the number of days between each. This is an extremely general figure. Plant growth rate is extremely fluid and can be subject to major variations day by day.
Why is the chlorophyll in chloroplasts less likely to produce fluorescence compared to extracted chlorophyll molecules? Most of the energy captured by chlorophyll in chloroplasts is converted into chemical energy by reducing electron acceptors in ETCs.
The chlorophyll fluorescence spectrum ranges from the 640 nm to 850 nm and has two peaks (690 nm and 740 nm).
So why aren’t most plants emitting red light? In a living plant, fluorescing chlorophyll would be a problem, as energy that is released as light cannot be used to make sugar .
The tissue water potential is measured with the help of thermocouple psychrometer . The portable field psychrometer is widely use for measuring drought resistance in segregating populations. The rate of photosynthesis during and after moisture stress is an important index of drought resistance.
Maintenance of adequate potassium (K) nutrition to plants has been found critical to mitigate drought stress. Potassium is the most important plant macro-nutrient with regard to cotton water relations, and it influences plant biochemical and physiological processes regulating to development and metabolism [118].
Plant indicators of wheat and soybean crop water stress | SpringerLink.
Leaf photosynthetic rate is measured by enclosing a leaf in a closed, transparent chamber and measuring the decrease in carbon dioxide concentration as a function of time . Light flux density is measured outside of the chamber and must be corrected for the chamber transmittance, which is 0.9.
Measuring photosynthesis via the production of oxygen
Oxygen can be measured by counting bubbles evolved from pondweed, or by using the Audus apparatus to measure the amount of gas evolved over a period of time .
By actually measuring the volume of oxygen gas produced by a plant , you can work out the rate at which photosynthesis is happening. The more oxygen given off, the higher (or faster) the rate of photosynthesis.